Excavations in one of the mounds near our camp disclosed very interesting composite structures.  One part of the walls consisted of large posts set in the ground and plastered over, forming a stuccoed palisade.  At right angles with this was a wall of cobble-stones, and among the buried debris were fragments of adobe bricks.  In one room of this group, at a depth of less than five feet, we struck a floor of trodden concrete.  Breaking through we found a huddle of six or seven skeletons, which, however, were not entire.

Rarely if ever was any object found in these rooms, except, perhaps, some stray axe, or some metates and grinding stones, and in one case a square stone paint pot.  But by digging below the concrete floors we came upon skeletons which seemed to have been laid down without regard to any rule, and with them were invariably buried some household utensils, such as earthenware jars and bowls, beautifully decorated; axes and mauls, fairly carved and polished.  One very rare object was secured:  a doubled-grooved axe.  The skeletons were badly preserved, but we were able to gather several skulls and some of the larger bones.

The floor material was so hard that only by means of heavy iron bars could we break through it.  As it was impracticable for us to make complete excavations, the number of rooms each mound contained cannot be stated.  There were in the immediate neighbourhood of Cave Valley at least ten or twelve separate groups, each of which had from four to eight rooms on the ground floor.  The entire district is richly studded with mounds.  On an excursion three or four miles down Piedras Verdes River I saw several groups of mounds, some of which, no doubt, contained many objects of antiquity.  On top of one low hill was a large group, and half a mile north of this another, 160 paces long and containing two oblong mounds.  Some of the mounds were ten or twelve feet high.

A very trustworthy Mormon informed me that there were no ruins, in caves or otherwise, along the river between this settlement and Colonia Juarez; nor were there any, he said, for a hundred miles south of Pacheco, though mounds could be seen in several places.  Therefore when I at last departed from Cave Valley, I took his advice and did not follow the course of the Piedras Verdes River down to San Diego, but led the pack train the safer, though longer, way over the regular road.  The country along the river was afterward explored by members of my expedition.  They came upon several small caves high up on the side of the canon, some of which had once been inhabited, to judge from the many potsherds and the smoky roofs; but no cave-houses were found until higher up the river, where some were seen in the sandstone cliffs.

I broke camp in Cave Valley on March 11th, and arrived on the same day at Old Juarez, a few miles from my camp at San Diego.  Now the weather was warm; the grass was sprouting, and I noticed a flock of wild geese going northward.